Since the 1970's, different types of tanks have been developed for wastewater treatment. In such tanks, aeration of wastewater is a key step in the treatment and results in a circulation of partially treated wastewater with incoming untreated wastewater. Blowers, air compressors, surface aerators and venturi aerators are used in the different wastewater treatment systems, all of which interact with the design of the tank in which they exist. Part of the function of these aerators is to create a circulation flow in the treatment tank to keep organic waste digestion processes going in an effective manner.
The aeration step of wastewater treatment requires a chamber in which aerobic digestion of organic solids can occur. Typically an actuated sludge process, or biofilm process occurs in the presence of such aeration. Most aeration chambers are in a cubic shape. In these chambers, there are some "dead corners" where low flow velocity in these corners causes organic solids to accumulate. The treatment efficiency of the overall process is affected by these "dead corners" where organic solids are not effectively digested. This in turn results in the build up of sludge in the bottom of the tank which must later be removed.
Wastewater treatment plants in different forms have been the subject of invention along with the processes used in the plants. Wastewater treatment plants are designed to digest organic material that is present in wastewater. As previously stated, a by-product of that digestion process is the formation of sludge which collects at the bottom of the waste treatment tanks. That sludge must later be removed and disposed of through a variety of means including incineration, landfill deposit, and other expensive and environmentally costly methods.
U.S. Pat. No. 4,505,831 to Graves discloses a wastewater plant having a particular tank design which is used in conjunction with an aerobic digestion process (see also U.S. Pat. No. 4,608,157 to Graves). This design comprises three chambers: a pretreatment chamber, an aeration chamber, and a final "clarification" or settling chamber. This design also comprises an opening at the bottom of a wall that separates the aeration chamber from the final clarification chamber to allow organic particles to settle out of solution in the final clarification chamber, falling to the bottom of the aeration chamber. However, when such particles reach the bottom of the aeration chamber they tend to remain there where they collect for subsequent removal due to lack of fluid circulation.
U.S. Pat. No. 3,966,608 to Mason et al. describes a liquid treatment apparatus for treatment of biodegradable material. This particular tank design also allows sludge or by-products from the aerobic process to sink to the bottom of the tank for subsequent collection. Again, a quiescent state exists at the bottom of the tank where sludge collects.
U.S. Pat. No. 3,972,965 to Higgins et al. describes a special aerator which is essentially the same as that disclosed in the U.S. Pat. No. 3,966,608 to Mason. As such the tank design embodied therein suffers from the same problem of dealing with sludge collecting at the bottom of a tank.
U.S. Pat. No. 3,966,599 to Burkhead et al. describes a method and apparatus for treating biodegradable waste products. Again, sludge collects at the bottom of this tank which is in a quiescent state and must subsequently be removed and disposed of.
In view of these prior inventions' creation of sludge, it therefore becomes important to create a wastewater treatment process in such a manner that the maximum digestion takes place thereby minimizing sludge production.
It is therefore an object of the present invention to provide fluid circulation in the aeration chamber of a wastewater treatment plant eliminating dead corners in order to achieve maximum digestion of organic solids.
It is a further objective of the present invention to enhance the settling action in the settling chamber thereby increasing the digestion of organic matter.
A further object of the present invention is to provide support for biofilm that is submerged in the wastewater being treated in the aeration chamber.